Your standard cherry microswitch on a standard Happ button is held by two pins, on arms connected to the button on one side. (There's a two-pronged retainer on the other side.) Pry lightly on the lower (or, if it's upside-down, upper) arm, then push up. (This is merely a more-detailed description that am_m was trying to explain.) Do the same with the other arm pin. Fini.